in the art of respiration devices, there are a variety of respiratory masks which cover the nose and/or mouth of a human user in order to provide a continuous seal around the nasal and/or oral areas of the face such that gas may be provided at positive pressure within the mask for consumption by the user. The uses for such masks range from high altitude breathing (i.e., aviation applications) to mining and fire fighting applications, to various medical diagnostic and therapeutic applications.
A requisite of such respiratory masks is that they provide an effective seal against the user's face to prevent leakage of the gas being supplied. Commonly, in prior mask configurations, a good mask-to-face seal has been attained in many instances only with considerable discomfort for the user. This problem is most crucial in those applications, especially medical applications, which require the user to wear such a mask continuously for hours or perhaps even days. In such situations, the user will not tolerate the mask for long durations and optimum therapeutic or diagnostic objectives thus will not be achieved, or will be achieved with great difficulty and considerable user discomfort.
A significant class of such respiratory masks are those which incorporate a flap seal of thin material so positioned about the periphery of the mask as to provide self-sealing action against the face of the user when positive pressure is applied within the mask. With this type of sealing action, the forces exerted by retention or straps which serve o hold the mask in confronting engagement on the face f the user are typically and intentionally quite small. If the flap seal is capable of conforming to he contours of the user's face without forming leak paths, the mask can be used with retention straps which exert little or no net force to push the mask against the user's face. Thus, the overall sensation of constrain m and confinement is dramatically reduced for the user. Such a mask, when properly adjusted, can be adapted to any positive internal mask pressure. The sealing flap will be self-sealing as long as there is no looseness in the strapping arrangement which would allow the mask to move away from the face further than the reach of the sealing flap when subjected to internal pressure.
Flap seal-type masks are subject to certain potential limitations, however. By design, the flap of such masks seals by laying flat against the user's face throughout its length. This action requires a close match between the contours of the face and those of the seal. If the match is not good, the seal will be ineffective. Further, the normal response of one applying the mask to one's face is to push the mask harder against the face if the mask does not seal. With the typical flap seal-type mask, increasing contact pressure against the face will not help to form an effective seal if the flap seal does not initially fit well to the facial contours. It may, however, lead to patient discomfort and other problems.
A number of the above-described disadvantages of flap seal-type masks were addressed and effectively overcome by the respiratory mask and accessories described in U.S. Pat. No. 4,907,584. Of the many beneficial features of the mask described therein, two in particular operate to eliminate the mask seal problems naturally attendant to such masks. First, the flap seal's supportive sidewalls include a plurality of reinforcement ribs to prevent collapse or buckling of the mask seal. Second, the mask includes spacer means for limiting deformation of the seal when in engagement with the user's face. The combined effects of these features result in a mask capable of reliable and comfortable sealing with a user's facial contours. In the featured embodiment, the spacer means consists of a spacer block attached to a pressure sensitive adhesive strip which can be adhesively applied to the mask. Due to the fact that each user's facial contours are different, that document acknowledges that a family of several differently configured spacer blocks should be made available to the consumer/mask-user to adequately accommodate the varied mask sealing requirements of the user population. As possible alternatives to a family of spacer blocks, that reference also suggests mechanically adjustable screw spacer apparatus or inflatable balloon-like spacers (neither of which systems is accompanied by illustration).
While the spacer means notion, per se, is meritorious, the various spacer means disclosed in U.S. Pat. No. 4,907,584 are somewhat undesirable in terms of cost and practicality. That is to say, a respiratory mask "package" including a family of spacer blocks necessarily results in a more expensive system than one requiring but a single spacer. Moreover, the construction of the spacer blocks is such that a user may have to perform substantial and potentially time-consuming trial-and-error experimentation in respect to proper selection of spacer size and placement before the appropriate sealing effect is achieved. Indeed, the user cannot adjust the position of the spacer block relative to the mask (and, ultimately, the user's face) unless the user completely removes the block and its adhesive base from the mask and positions the block at another site on the mask. Moreover, the mask must be removed from the user's face each time the position of a spacer block is adjusted or a different spacer block is applied. As to the un-illustrated adjustable screw spacer mechanism and the inflatable balloon-like spacer, it will be readily appreciated that such constructions would likely be substantially more complex and, therefore, costly than a family of interchangeable blocks.
An advantage thus exists for a respiratory mask including a single block-like spacer means for limiting deformation of the mask seal when in engagement with a user's face, and means carried by the mask for enabling quick, easy and continuous adjustment of the vertical position of the spacer means to achieve optimum user comfort and sealing effect.